On the perception of stress position by French listeners: An EEG investigation.

In this EEG study, we examined the ability of French listeners to perceive and use the position of stress in a discrimination task. Event-Related-Potentials (ERPs) were recorded while participants performed a same-different task. Different stimuli diverged either in one phoneme (e.g., /ʒy'ʁi/-/ʒy'ʁɔ̃/) or in stress position (e.g., /ʒy'ʁi/-/'ʒyʁi/). Although participants reached 93% of correct responses, ERP results indicated that a change in stress position was not detected while a change in one phoneme elicited a MisMatchNegativity (MMN) response. It results that in the early moments of speech processing, stimuli that are phonemically identical but that differ in stress position are perceived as being strictly similar. We concluded that the good performance observed in behavioral responses on stress position contrasts are due to attentional/decisional processes linked to discrimination tasks, and not to automatic and unconscious processes involved in stress position processing.

Does accentual variation in the pronunciation of French words influence their recognition? It depends on the ear of presentation.

This repetition priming study examined how word accentual variation in French is represented and processed during spoken word recognition. Mismatched primes in the accentual pattern were less effective than matched primes in facilitating target word recognition when the targets were presented in the left ear but not in the right ear. This indicates that in French, the accentual pattern of words influences their recognition when processing is constrained in the right hemisphere. This study pleads in favor of two memory systems, the one retaining words in an abstract format and the other retaining words in their various forms.

The effect of regular rhythm on the perception of linguistic and non-linguistic auditory input.

Regular distribution of auditory stimuli over time can facilitate perception and attention. However, such effects have to date only been observed in separate studies using either linguistic or non-linguistic materials. This has made it difficult to compare the effects of rhythmic regularity on attention across domains. The current study was designed to provide an explicit within-subject comparison of reaction times and accuracy in an auditory target-detection task using sequences of regularly and irregularly distributed syllables (linguistic material) and environmental sounds (non-linguistic material). We explored how reaction times and accuracy were modulated by regular and irregular rhythms in a sound- (non-linguistic) and syllable-monitoring (linguistic) task performed by native Spanish speakers (N = 25). Surprisingly, we did not observe that regular rhythm exerted a facilitatory effect on reaction times or accuracy. Further exploratory analysis showed that targets that appear later in sequences of syllables and sounds are identified more quickly. In late targets, reaction times in stimuli with a regular rhythm were lower than in stimuli with irregular rhythm for linguistic material, but not for non-linguistic material. The difference in reaction times on stimuli with regular and irregular rhythm for late targets was also larger for linguistic than for non-linguistic material. This suggests a modulatory effect of rhythm on linguistic stimuli only once the percept of temporal isochrony has been established. We suggest that temporal isochrony modulates attention to linguistic more than to non-linguistic stimuli because the human auditory system is tuned to process speech. The results, however, need to be further tested in confirmatory studies.